Communication system



3 Sheets-Sheet i Emma GEE COMMUNICATION SYSTEM J "A. KRUMHANSL Er AL INVENTORS f/fi/POLD GOLDBERG Original Filed Feb. 9, 1946 Oct 24, 1950" Oct. 24, 1950 I J. A. KRUMHANSL EI'AL R 23,283

' COMMUNICATION SYSTEM '3 Sheets-Shem; 2

Original Filed Feb. 9, 1945 M/XEI? .2 on

H i, D H l: INVENTORS 13d W/YROLD GOLDBERG JHMEJ a. many/yams; BY 5 HT TOR/YE Y Oct. 24, 1950 J. A. KRUMHANSL ETAL Re. 23,288

COMMUNICATION SYSTEM Original Filed Feb. 9, 1945 3 Sheets- Sheet 3 .1 wmmmmmq INVENTORS H/MOlfl 60L 085/76 mm f7 7' 7' ORA E Y Reissued Oct. 24, 1950 COMMUNICATION SYSTEM James A. Krumhansl, Ithaca, N. Y., and Harold Goldberg, Washington, Stromberg-Carlson Company,

New York.

Original No. 2,467,486, d No. 646,616, February D. 0., assignorsto a corporation of aged April '19,. 1949,. Serial 1946. Application for reissue'April 6, 1950, Serial No. 154,416

Matter enclosed in heavy brackets I: appears reissue specificationgmatter printed in italics indicates the additions made by reissue 14 Claims.

This invention relatesto communication systems and more particularly to detecting means for such systems.

It has been proposed to transmitintelligence inthe form of a train of pulses spaced apart or coded according to a function of time as well'as a function of the-amplitude of a modulating volt age representing the intelligence to be transmitted. One object of this invention is to providein'such a system an improved method of and means for translating or recreating close facsimile of the original-intelligence.

While our invention is particularly useful in pulsecommunication systems it is not limited thereto and the principles of the detecting system described hereinafter are also applicable to other forms of communication including amplitude -modulation radio transmission systems. It is, therefore, another object of our invention to provide newand improved detecting means for communication systems generally.

The-foregoing objects are achieved by providing a receiving system including an envelope detector. This detectormay comprise two electrondischarge devices, each including 'an anode, a. cathode, and. a controlielectrode or. grid. The discharge. devices. are inversely connected ,1. e., the anode ofone is connected to'the cathode of the other and the cathode of the one is'connected to the anode-of the-other. A'capacitor is connected between each of these anode-cathode connections and ground. A voltage. representing a desired characteristic of the received signal is applied across one of the capacitors. One or the other of the dischargedevices is rendered conductive at predetermined times which causes the instantaneous charge on the capacitor receiving-the signal to be transferred to the other capacitor. The voltage appearing across the other capacitor is applied to a suitable audio system for reproduction.

Further objects and advantages: will become apparent: as the following description proceeds. For a better understanding of our invention, reference 'ismade-to the following description andto the accompanying drawings in which:

' Fig. 1= is: a schematic diagram illustrating the application ofour invention to a pulse communication system,

Fig. 2 is achart useful in explainingthe oper-- ation of the system shown in Fig. 1,

Fig. 3 is a second application of-our invention to a pulse communication system embodying push-pull principles,-

in the original patent butforms no part of this Figs. 4 and 5 are charts'illustrating the operation'of the circuit shown in Fig. 3,

Fig. 6 is a schematic diagram illustrating the application of our invention to an amplitudemodulated system, and

Figs. 7 and 8' are charts illustrating the operation of the circuit-shown in Fig. 6.

Referring to Fig. 1, there is illustrated a receiving system adapted toreceivespace or position-modulated pulses such as would be trans-- 'mitted in the system shown, described and:

claimed in the co-pending applications of Harold Goldberg, Serial No. 646,614, now abandoned,

' filed February 9, 1946, and'Serial No. 646,615, filed February 9, 1946, now Patent No. 2,466,230, issued April 5, 1949, and assigned to the'same assignee asthe present invention. The receiving system of our invention includes a suitable antenna a combined local oscillator and mixer unit repre F. amplifier and sec sented by block 2, and an I. ond detector indicated by the-block 3. If desired, the signals may thenbe' limited or clipped so that all signals at this stage of reproduction are positive pulses of constant" amplitude. Means for ac-- complishing this purpose isnot shown known in the art.

There is provided means-indicated by numeral out is well 4 for derivinga-delayed pulse from each received pulse for causing operation of a decoder 5 which in turn provides voltage for causing operation of theenvelope detector 6 at predetermined times.

Thedelay circuit l-utilizes a blocking oscillator and makes use of the fact that the output of a blocking oscillator may not be unidirectional, but may have considerable overshoot, i. e., during a part of a complete oscillation, the voltage reverses: The-overshoot, of course, is delayed with respect to-the main peak-of the pulse by a, definite time-interval;

8 (of R-Ciproduct'much-greater than the time In order to amplify and sharpen the received pulses, there is provided the blocking oscillator i1- lustrated in'Fig. 1 comprising an electrondis-L- charge device I, transformer l0 and R-C network the cathode 9 of the dis- Positive. pulses from the second: areusupplied to ing ll of the transformer l and trigger the oscillator or generator circuit to cause a voltage to appear across the R-C network. Since the received pulses are differently spaced, a train of pulses will be produced having equal maximum amplitudes spaced similarly to the received 1 pulses.

The transformer I0 is provided with two additional windings l and I6. The connections to these windings are made in such a manner that output voltages are reversed in sense, the sense of the voltage appearing across winding I5 being reversed or inverted with respect to that across the winding l3 and that appearing across winding IS. The output from winding I5 is applied to the tooth wave generator including an electron discharge device I! which may be a triode having an anode I8 connected to a suitable source of positive'potential, a control electrode l9 connected to one terminal of windingjl5 of transformer l0, and a cathode 20. An R-C network comprising resistor 2| and electric storage means such as condenser 22 connected in parallel therewith is inserted between cathode and ground. The R-C constant must be equal to the R-C constant of the coder in the transmitter as explained in the above-identified co-pending applications. The other terminal of transformer winding I5 is grounded. Inasmuch as inverted pulses are applied to grid [9, the overshoot portions of the pulses developed in the delay circuit trigger the discharge device I1 to charge condenser 22 to a maximum amplitude. Between operations of device l1, the voltage across condenser 22 decreases to minima which lie on a. curve (represented by the dashed line 31 in Fig. 2) representing the original intelligence. As is fully explained in the above-mentioned copending applications, the decoder is caused to re-charge the condenser each time the voltage across cays to the point represented by the junction of the dashed line 31 and the voltage line 23 (Fig. 2).

In order to separate the envelope from the sawtooth wave 1. e. to detect the minima of the pulses in the decoderoutput, the demodulator or envelope detector 6 is provided. The envelope detector in this form of our invention comprises two electron discharge devices 25 and 26 which may be of the triode type including anodes 21 and 28 respectively, control electrodes 29 and 30 respectively, and cathodes 3| and 32 respectively. Anode 21 is connected to cathode 32, cathode 3| is connected to anode 28, and the control electrodes are connected together. The output of the decoder is impressed on the connection between anode 28 and cathode 3|. Uninverted or undelayed pulses substantially corresponding in time to the original pulses are applied to the control electrodes 29 and 30 by means of a connection between the control electrodes and one terminal of the winding I6 of transformer III, the other terminal of the winding It being grounded. Electric storage means such as a capacitor 33 is connected between ground and the connection joining anode 21 to cathode 32.

The recurring voltage generated in the decoder and appearing across the capacitor 22 is impressed on the anode 28 and :cathode 3|.

As briefly described above the voltage across capacitor 22 decays exponentially until the oscillator or generator is again triggered and the next charging voltage is generated. The spacing between. the charging periods is dependent upon the amplitude of the original signal. Thus, as

decoder 5 which comprises a saw the R-C network de- 26 is cut off. In the a output from the condenser audio system (not shown) sistor 4|.

nite time interval voltage across capacitor 33 is less the amplitude of the signal voltage increases the generator triggers more rapidly and the decay portion of the cycle is halted earlier and vice versa. Obviously, the overshoot of the pulses utilized to trigger the decoder takes place at a defipreceding the next succeeding pulse. Therefore, by operating the decoder by means of the delayed or overshoot pulse the envelope detector is rendered operative prior to the receipt of the undelayed pulse by a time equal to the above-mentioned interval. The capacitor 33 is at that time connected across the capacitor 22 through the conducting path of one of the discharge devices so that capacitor 33 is charged to the same voltage as that across capacitor "22 at that instant. The capacitance of capacitor 33 is made substantially less than that of capacitor 22 so that the voltage of capacitor 22 is substantially unaffected by the transfer of charge from capacitor 22 to capacitor 23.

A double set of discharge devices or tube elements is necessary, whether in a single envelope or in the form of a pair of tubes 25 and 26 as shown, because the voltage across capacitor 33 at any given time may be greater or less than that across capacitor 22 depending upon the direction of change of the voltage across capacitor 22. If the voltage across capacitor 33 is greater than that across capacitor 22, electron discharge device 25 is rendered conductive whereas, if the than that of capacitor 22, electron discharge device 26 is rendered conductive. The discharge devices are so biased that when the pulse subsides conduction through discharge device 25 or discharge device embodiment of our invention illustrated in Fig. 1 the necessary negative bias is supplied through a resistor 34 connected between the control electrodes and a suitable source of negative potential. However, the potential at the upper end of resistor 2| and condenser 22 is decoder is insuflicient, 1

In order to prevent transients, there may be provided a resistor 35 in the connection between the transformer winding l6 and thecontrol elec-- trodes 29 and 30.

In order to prevent substantial decrease in charge across condenser 33 during the intervalsbetween samplings of the voltage across condenser 22 or, in other words, when neither of the discharge devices 25 and 26 is conducting, the 33 is connected to the through a. high impedance device whereby discharge between pulses is prevented. In Fig. l, the high impedance device takes the form of a cathode follower, including an electron discharge device ,33 which may be a triode. The upper end of condenser 33 is connected to the control electrode 39 of the discharge device 38. The cathode 40 of the discharge device is connected to ground through a suitable re- Since the input impedance of the cathode follower is very high because of the absence of grid leak, there will be no appreciable discharge from capacitor 33 between pulses.

Referring to Fig. 2, the full line 36 represents the voltage appearing across capacitor 33 and, of course, is also representative of the voltage appearing across resistance. This voltage may be filtered and fed to a suitable audio system for reproduction into soundsignal into a suitable intermediate frequency.

The intermediate frequency signals are amplified and detected in the intermediate frequency a'ijn plifie'r and second detector represented by the block 44-. The positive pulses derived iromtne second detector are supplied through the-winding 45 of the transformer 46' to the envelope detector 41 which serves as a push-pull demodulator are functions to detect the envelopes of the alternate minima, and to combine the resulting push-pull output through the-agency of a delay circuit 40 and decoder 49 Delayci'rcuit 48 comprises a triggered" blocking oscillator including an electron discharge deviee 50, i1l'ustrated as of the trlode type havingg'a cathode 5I, a control electrode 52 and ananode 53. The blocking oscillator not only serves as a source of pulses for a timing wave but also as a pulse amplifier, sharpener; and clipper. The R-C network 54 connected in the cathode lead provides a bias voltage for the control electrode or grid 52 which normally keeps" the oscillator circuit from oscillating. A positive pulse from the second detector triggers the oscillator circuit and causes it to generate a single blocking oscin lator pulse. The oscillator pulses are 'of' constant amplitude and because of their form it is possible also to obtain a' delayed pulse as described above by reversing the sense of the out-'- put pulse from the transformer and utilizing the overshoot as a trigger pulse, the delayed pulse or overshoot thus providing a means for obtaining a delayed pulse without the use of delay'net works. The delayed pulse appearing on the anode 53 of the electron discharge device is transferred to the decoder 49 by means of ppri mary winding 55 and secondary winding 56 of transformer 51. The decoder 45 comprises" a saw tooth generator including an electron discharge device 58 having an anode 59 connected to a suitable source of positive potential, a con trol electrode 80 connected to the secondary winding 56 of transformer 51, and a cathode SI connected to ground through an R -C' network consisting of resistance 62 and capacitor 63 con nected in shunt relationship. The delayed pulse is thus applied to control electrode to cause the generation of a voltage each time a pulseis received. A positive pulse applied to the control electrode of the decoder causes the condenser 63 to charge to a fixed value. The subsidence" of the positive pulse results in the cut-off of the discharge device 58 so that the condenser 63 discharges exponentially through resistorli! as iri*- dicated graphicallydn Fig. 4 wherein numeral 54 represents the recurring voltage peaks. There is provided a scale-of-two counter 55 comprising triodes- 66 and 61 which function after the manner of an Eccles-Jordan circuit to produce two rectangular wave outputswhich are capacitively coupled to diodes G8 and 59 respectively. The diodes act as direct current 're-" storers. The output of restorer B8 is added to the pulse in secondary winding I0 of transformer 51 and the output of diode G9 is added to" the received pulse in secondary winding! I of transformer";

"rne'puslapuii envelope detector 41- may coin:- prisefcuii'electrori discharge devices 1:3,; 14, I5, and- 10".- Cathode 1'1 and anode 18 of discharge es lean-a 14,- resp'ectively, and anode I9 and cathode f of discharge devices 15 and 16, respectively are connected together and to the upper enact capacitor 63 of decoder 49. Anode 8]": and cathode- 82 of electron discharge devices I3 and M; respectively, are connected to the upper side or capacitor 83 as viewed in Fig. 3. Cathode 84 and anode 85 of discharge devices 15 and 16 respectively, are connected to the lower side of a capacitor 86. The lower side of capacitor 83 and the upper side of condenser 86 are connected together and to ground. The combi'ned'vol'tages' appearing in transformer winding I0 are applied to the control electrodes 81 and 88 of electron discharge devices 13 and I4, respectively, and the combined voltage appearing across winding H is applied to control electrodes 89 and: 90' of discharge devices I5 and I6, respectively. In 'this manner the two envelope de teeters-win be activated alternately and each by itself determines the alternate minima of the decoder, and the outputs of the two detectors are; therefore, push-pull variations of theoriginal modulation. r g The twodetectors are respectively coupled by the condensers 83 and 86 to cathode followers ineluding the electron discharge devices BI and B2. The transformer winding 93 in the cathode circuits of the followers combine the push-pull outpu'ts'through a secondary winding 94 to a suitable output circuit for reproduction.

' Fig. 4' depicts the action taking place in the circuit of Fig. 3. As stated above the voltage appearing across the condenser 63 is represented by the numeral 64 in-Fig'. 4. The dashed line 95 represents the charge on one of the condensers as; for example, condenser 8 3 andthe dashed line 56 represents the voltage onthe other condenser 86; The-resultant or combined voltage is shown by-the-stepped liheSI of Fig. 5. In each of Figs. 4" and 5 the-envelope of the minima which is the signal to be reproduced is represented by the numeraraa:

M invention is not limited to pulse systems. Forexam ie, it is also applicable to amplitude modulation; particularly in cases where the envelope frequency is not much lower than the carrier'- frequency. Fig. 6 illustrates an application of the principles of our invention to amplitude' modulation. There is shown a suitable antenna-I o'oror receiving the signals transmitted from a suitable amplitude modulation transmit ter; A suitable-local oscillator and mixer stage is indicated" by the numeral IE1 and the numeral I02 is used to-indicate the insertion'of a suitable I. F. amplifier and second detector. The output ofthesecond detector is fed to a cathode follower circuit including an electron discharge device I03 including an anode I04 connected to a suitable source of positive potential,- a, control electrode I05 connected to the output of the second detector and a cathode I06 connected to ground througha-r'esistor' I01; A capacitor I08 is connected in shunt with the resistor I01. The time constant o'fcapacitor I08 and resistor IIII should be short sothat the condenser discharges before itis're-cha-rgedby operation of discharge device I03. The voltage appearing across the capacitor I08 is applied to one of the inversely connected electron discharge devices I09 and I I0 respectively' in similar manner to that illustrated in Fig. 1; Condenser" II I-' is connected between ground and the other anode-cathode connection as well as to a cathode follower output device I I2. It will be noted that the voltagejrepresente ing the signal rather than the delayed voltage i applied to the first mentioned anode-cathode connection. In the system shown in Fig. 6;it is not desired to compare the voltage changes; prior to the reenergization of the discharge device I 03 as was the case in the pulse receiving system, but it is desired to sample the voltage across capacitor I08 at the peaks of the modulated ;car-- rier waves. In order to render conductive one .or the other of the discharge devices I09 and H the output of the second detector is fed through means I I3 for clipping the signal, means II4 for squaring the clipped signals and difierentiating means I I5 comprising a capacitorII'Ii and a resistance I I! to provide trigger pulsesfor a delay multi-vibrator H8. The operation of the system shown in Fig. 6 is illustratedin Fig. '7 wherein at A there are illustrated a few cycles of the modulated carrier, at B thesquared waves appearing in the output of means II4, andat G and transformer I36.

the peaked pulses derived from the .difierentif I ating means II5 which are applied as trigger pulses to the multi-vibrator I I0. The multi: vibrator comprises discharge devices I19 and I20, the circuit connections beingsuch that device II9 is normally non-conductive and devicc. I20 normall conductive. The trigger pulses applied to the control electrode I2I. of electron discharge device II'9 render that device conductive and discharge device I20 non-conductive to establish positive pulses at the anode of device I20. These pulses are impressed on a blocking oscillatorcomprising an electron discharge device I 3I which may be a triode having an anode I32, control electrode I33 and cathode I34. An R 0 network of suitable R-C product is connected between the cathode and ground and comprises re sistance I38 and capacitor I39. The pulsesare impressed on anode I32 through a suitable cou; pling capacitor MI and also to one end of wind-, ing I35 of transformer I36, the other end of winding I35 being connected to a suitable source of positive potential. Winding I31, of. transformer I36 is connected from ground to-control electrode I33 through a suitable gridleak-grid condenser combination. The cathode I 34. is also connected through resistance I40 to.,a suitable source of positive potential, thereby establishing bias for discharge device I3I. Capacitor I-4I and winding I35 serve to differentiate the pulses the negative going peak of the differentiated-pulses appearing as positive voltage pulses in winding I31, causing conduction in device I 3I .The dip in anode voltage is transformed intoapositive pulse in winding I42 of transformer I36. 5;; These pulses are applied to the control electrode I2! and I22 of the, electron discharge devices I09 and III] respectively ofthe envelope detector. Whenever either of the discharge-dc; vices I09 and H0 becomes conductive, capacitor II I assumes the voltage appearing across I00 ca pacitor at that instant. As seen in Fig. 8, ifthe. envelope detector operates at the peaksofcarrier current wave, the voltage across capacitor III is stepped as indicated by the numeral I23 in Fig. 3. In Fig. 8 the carrier voltage is,repre-. sented by the numeral I24 and the envelope by the numeral I25. 1 To enable adjustment of the circuitto cause sampling and equalization of capacitor voltages at the carrier peaks there is provided means-for adjusting the bias on the control electrode of the I electron discharge device I20'iri the form of a; suitable potentiometer or resistance I26 connected between the control electrode I'2'I of 1115- charge device and;v a suitable source Of posi tive-potential, The setting of control I26 is not particularly critical inasmuch as the relatively gradualwchange in voltageover a relatively long period of time; at the peak of the carrier wave will. ive substantially the same results as can be seenby'reference to, Fig. '7, D. While conditions 4?? exaggerated for purposes of illustration, it will be seen that if the pulses derived from the multi-vibrator .occur at any time between the dotted positions indicated by the numeral I30 the,-vol tage across capacitor II I will be difierent only to a minor degree from that which would result if the envelope detector operated at exactly the maximum of the carrier wave.

'I-fhe circuit of Fig. 6 ma be simplified by omitting the last mentioned blocking oscillator I3I Instead, the negative pulses appearing at the anode of discharge-device, I I0 canbe differentiated and the positive g ing. part of the diiferentiatedpulse employed to trigger the envelope detector.

,Whilewe have shown anddescribed particular embodiments of our invention it will be obvious to thoses'killed in the art that changes and modiiications may be made without departing from our invention in its broader aspects and we,- therefore, aim in the appended claims to cover all such changes and modifications as fall Within the true spirit andscope of our invention. I

"What we claim as new and desire to secure by LettersPatent of the United States is:

1.1a a communication system having transmitting .means and receiving means, the receiving means including means for detecting intellig' ence to be reproduced including a pair of electron discharge devices, each of said devices having an anode, a cathode, and a control electrode, means for inversely connecting said anodes and cathodes and means for connecting said control electrodes, one of said anode-cathode connections constituting a first input terminal and said control electrode connection constituting a secs ond input. terminal to said detecting means, a first electric storage means connected between said,'first input terminal and ground, a second electric storage means connected between the other anode-cathode connection and ground, means for impressing a voltage representing the received signal, on said first input terminal, and means actuatcdby the received signal and coupled to said second input terminal to render conductive one or the other of said electron discharge devices depending upon the relative potentials at the anode-cathode connections at predetermined times with respect to the received signal whereby the potential of said first electric storage means is transferred to said second electric storage means during such conductive periods.

2. In a communication system having transmitting ,and receiving means, said receiving meansincluding means for detecting the intelligenceto be reproduced including a pair of electron-discharge devices, each of which devices has anianode, a, cathode, and a control electrode, said anodes and cathodes .being inversely connected and. said control electrodes being connected together, one of said anode-cathode connections constituting a first input terminal of said detectmeans, and said control electrode connection constituting a second input terminal, a third elec "a tron discharge device-having an anode, a cathode and a control electrode, a resistance connected between the cathode of said third discharge device and ground, a first capacitance connected in shunt with said resistance, a second capacitance connected between the other anodecathode connection and ground, means'rlor impressing a voltage representing the receivedv signal on the control electrode of said third device whereby the charge on said first capacitance corresponds to a characteristic of the received signals, the ungrounded end of said first capacitance being also connected to said first input terminal whereby the potential of said first capacitance is transferred to said second capacitance whenever either of said pair of electron discharge devices is rendered conductive, and means for rendering one or the other of said pair of electron discharge devices conductive at desired times.

3. In a communication system having transmitting and receiving means, said receiving means including means for detecting the intelligence to be reproduced including a pair of electron-discharge devices, each of which devices has an anode, cathode, and a control electrode, said anodes and cathodes, being inversely connected and said control electrodes being connected together, one of said anode-cathode connections constituting a first input terminal of said dotecting means and said control electrode connection constituting a, second input terminal, a third electron discharge device having an anode, a cathode and a control electrode, a resistance connected between said cathode of said third discharge device and ground, a first capacitance connected in shunt. with said resistance, a second capacitance connected between-the other anode-cathode connection and ground, means for impressing a voltage representing the received signal on the control electrode of said thirddevice whereby the charge on said first capacitance corresponds to a characteristic of the received signals, the ungrounded end of said first capacitance being also connected to said first input terminal whereby the potential of said first capacitance is transferred to said second capacitance whenever either of said pair of electron discharge devices is rendered conductive, means for rendering one or the other of said :pair of electron discharge devices conductive at desired times, and high impedance output means coupled to said second capacitance.

4. In a communication system having means for transmitting and receiving signals, said receiving means comprising means for detecting intelligence to be reproduced including a pair of electron-discharge devices, each of which devices has'an anode, a cathode, and a control electrode,.

said anodes and cathodes being inversely connected ands'aidcontrol electrodes being connected together, one of said anode-cathode connections constituting a first input terminal to said detecting means and said control electrode connection constituting a second input terminal, afirst capacitance connected between said fir t input terminal and ground, a second capacitance connected between the other anode-cathode connection and ground, means for impressing a voltage representing the received signal on said first input terminal, and means actuated by the received signal and coupled to said second input terminal to render conductive one or the other of said electron discharge devices depending upo'njrela tive potentials at the anode-cathode connection at predetermined times with respect to the re-- ceived signal, whereby the potential of said first capacitance is transferred to said second capacitance during such conductive periods, the capacity of saidxsecond capacitance being substantially less than that of said first capacitance so that the potential on said first capacitance is not substantially affected by the transfer of potential from said first to said second capacitance.

5. In a communication system including means for transmitting and receiving pulses representing intelligence to be communicated, said receiving means including a'pair of electron discharge devices, each discharge device having an anode, a cathode and a control electrode, said anodes and cathodes being inversely connected, means for impressing the received pulses on said control electrodes, electric storage means connected between each anode-cathode connection and ground, means ,for reproducing each received pulse after a predetermined time delay, means for charging one of said storage means in accordance with the voltage of said delayed pulse, and means for applying said voltage to said second storage means whenever either discharge device is rendered conductive.

6. Ina communication system including means for transmitting and receiving pulses representing intelligence to be communicated, said receiving means including a pair of electron discharge devices each having'an anode, a cathode and a control electrode, said anodes and cathodes being inversely connected, means for impressing the received pulses on said control electrodes, electric storage means connected between each anodecathode connection and ground, means for reproducing each received pulse after a predetermined time delay, means for charging a first of said storage means in accordance with the voltage of said delayed pulse and :means for applying said voltage to the second of said storage means whenever either discharge device is rendered conductive, said second storage means having a capacitance substantially less than the capacitance of said first storage means so that the voltage on said first storage means is substantially unaffected by the transfer of voltage to said second storage means.

- 7. In a communication system including means for transmitting and receiving pulses representing intelligence tobe communicated, said receiving means including a pair of electron discharge devices, each of said'devices having an anode, a cathode, and a control electrode, said anodes and cathodes being inversely connected, means for impressing voltages representing the received pulses on said controlelec'trodes, a capacitor connected between each anode-cathode connection and ground, a source of recurring voltage, means for controlling the time of recurrence of said recurring voltage in accordance with a characteristic ofthe received pulses, and means for applying said recurring voltage to one capacitor whereby the potential of said capacitor is applied to the other capacitor whenever either discharge device is conducting whereby the changes in voltage across said other capacitor follow the voltage representing the intelligence transmitted.

8. In a communication system including means for transmitting and receiving pulses represent ing intelligence to be communicated, said receiving means including a'pair of electron discharge devices, each of said devices having an anode, a cathode, anda control electrode, said anodes and cathodes being inversely connected, means for impressing voltages representing the received intelligence on said control electrodes, a capabl tor connected between each anode-cathode-con nection and ground, a source of recurring voltage, means for controlling the'times of recurrence of said recurring voltage in accordance with the times of repetition of the intelligence voltage, and means for applying said recurring voltage to one capacitor whereby the potential of said one capacitor is applied to the other capacitor whenever either discharge device is conducting so that the changes in voltage across said other capacitor follow the voltage representing the intelligence transmitted. I 9. In a communication system including transmitting means and receiving means, said receiving means having means for detecting intelligence to be reproduced comprising a pair of electron discharge devices, each of said devices having an anode, a cathode, and a control electrode, said anodes and cathodes being inversely connected, means for impressing voltages representing the received intelligence on said control electrodes, a capacitor connected between each anode-cathode connection and ground, a wave generator including an electron discharge device and a resistance-capacitance network, said generator being normally inoperative, means for impressing a delayed counterpart of said signal on the control electrode of said electron discharge device for rendering operative said generator to produce a voltage across said network, and means for impressing said voltage on one of said anodecathode connections, a capacitor connected between the other anode-cathode connection and ground whereby the voltage generated by said generator is applied to'sald capacitor whenever said generator is operative.

10. In a communication system including means for transmitting and receiving pulses representing intelligence to be communicated, said receiving means including a pair of electron discharge devices, each of said devices having an anode, a cathode and a control electrode, said anodes and cathodes being inversely connected, means for impressing said pulses on'said control electrodes, means for obtaining a delayed counterpart of said pulses, the delay interval being less than the interval between'successive pulses, a first capacitor connected to be charged by said counterpart, means permitting at least partial dissipation of said charge between charging inter-' vals, means for impressing the-potential of said first capacitor on one of saidanode-cathode connections, and a second capacitor connected to the other of said anode-cathode connections whereby" said second capacitor samples the charge on said I first capacitor during conduction ofeither of said" discharge devices, the voltage across said second, capacitor reproducing closely the voltage corre-.-

sponding to the intelligence transmitted.

11. In a modulated wave communicationsys tem having means for transmitting and receiving modulated signals, said receiving means includ-- ing means for reproducing the intelligence received from said transmitting means, said means including a pair of electron discharge devices, each device having an anode,-a cathode and a control electrode, said anodes and cathodes being inversely connected, a capacitor connected between each anode-cathode connection and ground, means for impressing a voltage corresponding to the modulated signals on one of said anode-cathode connections, and means utilizing the received signal and said control electrodes for rendering conductive on or the other of said discharge devices at substantially the peaks of each cycle of the received-signal carrier whereby the voltage of the capacitor connected to said one anode-cathode connection is applied to the other capacitor each time either discharge device is rendered conductive.

.12. In a modulated wave communication system including transmitting and receiving means, said receiving means including means for detecting and reproducing the received intelligence com-' prising a pair of electron discharge devices, each of said discharge devices having an anode, a cathode, and a control electrode, said anodes and cathodes being inversely connected, a third electron discharge device having an anode, a cathode, and control electrode, resistance means 'connected between the last mentioned cathode and ground, capacitance means connected in parallelwith said resistance means, means for impressing" the received signal on the'control electrodeof said third discharge device, means for impressing the voltage appearing across said capacitance means on one of the anode-cathode connections, capacitance means connected between the other anode-cathode connection and ground, and means for rendering one or the other of said discharge devices operative at predetermined times whereby the potential of said first capacitance means is transferred to said second capacitance means.

13. The method of reception of pulse modulated signals which comprises receiving said pulses, developing a voltageof a given value for each pulse, developing a second voltage correaccordance with afu'nction of time for an interval terminated bythe succeeding pulse in the" train whereby the minima of the said second voltages at the termination of the'several intervals define an envelope corresponding to the original signal, utilizing said first voltage to sample said second voltage at approximately the times of occurrence of said minima, and translating the sampledvoltages into sound.

14. In combination, a source of energy pulses modulated in repetition period; a saw tooth wave generating and shaping means responsive there-v to; an energy storage circuit; and means momentarily applying the output of said generating and shaping means to said energy storage circuit near the pealcof each of the sawtooth excursions of said output.

JAMES A. KRUMHANSL. I HAROLD GOLDBERG. REFERENCES CITED The following references are of record in the file of this patent:

- UNITED STATES PATENTS Number Name Date 2,113,011 White Apr. 2, 1938 2,335,265 Dodington Nov. 30, 1943 2,404,306 Luck July 16, 1946 2,406,019 Labin Aug. 19, 1946 2,406,978 Wendt Sept. 3, 1946 2,411,573 Holst Nov, 26, 1946, 2,412,994 Lehmann Dec. 24, 1946 2,415,567 Schoenfeld Feb. 11, 1947 2,415,918 Thomas Feb. 18, 1947 2,416,308 Grieg Feb. 25, 1947 2,436,890 Higinbotham Mar. 2, 1948i Goldberg, Mar, 14, 1950 

